In current liquid crystal display devices, in order to enhance the optical quality of display areas, for example, to increase the brightness and its uniformity, optical film sets are usually disposed in the backlight modules. When an optical film set is applied in a direct type backlight module, usually the optical film set is directly disposed on a diffusion plate, and when an optical film set is applied in an edge type backlight module, usually the optical film set is directly disposed on a light guide plate.
FIG. 1 is a cross-sectional view of a portion of a conventional liquid crystal display. For example, a liquid crystal display 100 is mainly composed of a direct type backlight module 104 and a liquid crystal display panel 102, wherein the backlight module 104 is disposed on a rear surface of the liquid crystal display panel 102 to provide back light for the liquid crystal display panel 102. The liquid crystal display panel 102 mainly includes a color filter 118, a transistor substrate 120 and a liquid crystal layer (not shown) held between the color filter 118 and the transistor substrate 120, wherein the color filter 118 is stacked on the transistor substrate 120. In addition, the liquid crystal display panel 102 typically further includes an up polarizer 116 and a down polarizer 122, wherein the up polarizer 116 is stacked on the color filter 118, and the transistor substrate 120 is stacked on the down polarizer 122.
The direct type backlight module 104 mainly includes a rear plate 106, at least one light source 108, a diffusion plate 110, an optical film set 112 and a frame 114. The light source 108 is typically a cold cathode fluorescent lamp (CCFL), and the light source 108 is disposed on the inner side of the rear plate 106. The frame 114 is usually set on the outer edge of the rear plate 106. The diffusion plate 110 is disposed on the light source 108 and is carried by the rear plate 106. The optical film set 112 is stacked on the diffusion plate 110 and is supported by the diffusion plate 110. The liquid crystal display panel 102 is disposed on the optical film set 112 of the backlight module 104, wherein the liquid crystal display panel 102 is carried and supported by the frame 114 set on the outer edge of the rear plate 106.
FIG. 2 illustrates a cross-sectional view of a portion of another conventional liquid crystal display. A liquid crystal display 200 is mainly composed of an edge type backlight module 204 and a liquid crystal display panel 202, wherein the backlight module 204 is disposed on a rear surface of the liquid crystal display panel 202 to provide back light for the liquid crystal display panel 202. Similarly, the liquid crystal display panel 202 mainly includes a color filter 216, a transistor substrate 218 and a liquid crystal layer (not shown) held between the color filter 216 and the transistor substrate 218, wherein the color filter 216 is stacked on the transistor substrate 218. In addition, the liquid crystal display panel 202 further includes an up polarizer 222 and a down polarizer 220, wherein the up polarizer 222 is stacked on the color filter 216, and the transistor substrate 218 is stacked on the down polarizer 220.
The edge type backlight module 204 mainly includes a rear plate 206, at least one light source 224, a light guide plate 210, an optical film set 212 and a frame 214. The rear plate 206 is mainly composed of a bottom plate 228 and a side plate 226, wherein the side plate 226 is usually set and stands on the outer edge of the bottom plate 228. The light guide plate 210 is disposed in the rear plate 206 and on the bottom plate 228, wherein a reflective sheet 208 is usually disposed between the bottom plate 228 and the light guide plate 210 to reflect and effectively employ the light emitted toward the bottom plate 228 of the rear plate 206. The light source 224 is usually a cold cathode fluorescent lamp, and the light source 224 is disposed on the inner side of the rear plate 206, on an inner side surface of the side plate 226 of the rear plate 206 and between the side plate 226 and a side surface of the light guide plate 210. The frame 214 is usually embedded on the side plate 226 of the rear plate 206, wherein a portion of the frame 214 extends on the outer region of the light guide plate 210. The optical film set 212 is stacked on the light guide plate 210 and is supported by the light guide plate 210. The frame 214 extends on the outer region of the light guide plate 210 and simultaneously presses on the outer edge of the optical film set 212. The liquid crystal display panel 202 is disposed on the optical film set 212 of the backlight module 204, wherein the liquid crystal display panel 202 is carried and supported by the frame 214.
In the direct type backlight module or the edge type backlight module described above, the optical film set is directly connected with and supported by the diffusion plate or the light guide plate, so that there is no gap between the optical film set and the diffusion plate or between the optical film set and the light guide plate. However, a gap, e.g., an air layer, may be needed between the optical film set and the diffusion plate or the light guide plate to be the medium of light transmission in a future optical design. In addition, a backlight module may not include a diffusion plate, considering the cost of a future display device. Accordingly, an improved support for the optical films will become important in the development of liquid crystal display devices.